1. Field of the Invention
This invention relates to an electric connector for electrically connecting a camera body with an accessory device such as interchangeable lens.
2. Description of the Related Art
Recently, as the trend of using electronics in the camera system advances, there are increasing proposals concerning the electric connector device between the camera body and the interchangeable lens through which the informations representing the focal length and the F-number at full open aperture of the interchangeable lens are electrically transmitted to the camera body.
Also, in recent years, electronic cameras usable in actual practice have been developed. For example, one of their types is that a microcomputer is built into the interchangeable lens, and gives and receives data to and from the microcomputer which is built within the camera body through a data connector, so that the diaphragm and the mechanism a focusing system are controlled.
In such a type, there is need to use an additional connector through which electrical power is supplied from the camera body to the interchangeable lens. Hence, in total, at least three common connectors with inclusion of the before-mentioned data connector and a ground connector common to both camera body and lens must be had in between the camera body and the lens.
In application of the conventional connector device to this type of electronic camera, however, if the contact of connector for power supply on the camera body touches any other contacts of connectors than the contact of connector for power reception on the lens in electrical conduction, it is highly possible that the electrical circuit within the interchangeable lens will be destroyed.
To solve this problem there have been previous proposals in U.S. Pat. Nos. 4,492,429 and 4,464,034, for example. According to these proposals, as coupling of the interchangeable lens to the camera body is carried out by rotating them about the optical axis relative to each other, establishment of the power supply to the interchangeable lens is made only when the rotating is complete. In more detail, although the data and ground connectors are allowed to contact with each other in the middle of the course of performing the coupling by rotating the interchangeable lens, it is the power connectors on the camera body and the lens that are brought into contact with each other by means of a lock mechanism for the interchangeable lens at the time of completion of the coupling rotation.
However, these prior known devices have problems that the operative connection between the power connector and the lock mechanism is of complicated structure, and that if a lock release button of the interchangeable lens is unintentionally pushed down, the power supply to the interchangeable lens is cut off at that time. Thus, faulty operations are apt to occur.
According to another proposal made in U.S. Pat. No. 4,637,704, the ground connector is arranged to become effective in retard of the coupling rotation of the interchangeable lens relative to the camera body after the data and power connectors have been effective (at the same time). For this purpose, the practical means is to differentiate the widths of all the connectors from one another, or their separations.
However, if the power and the data connectors have potentials before the ground connector is grounded, a possibility will arise that as the integrated circuit within the interchangeable lens has been latched up, the later connection of the ground connector to the circuit earth destroys the IC.
It is to be noted that U.S. patent application Ser. No. 012,862 filed Feb. 10, 1987 assigned to the assignee of the present invention discloses the electric connectors as associated with the mount device of the camera. In this connection, it should be pointed out that the electric connectors of this preceding patent application are so arranged that their individual contact timings take place almost simultaneously, and, therefore, this arrangement is different from that of the present patent application described below.